Centrifugal switch



May 13. 1924.

B. F. DAY ET AL 'CENTRIFUGAL SWITCH Filed June 17. 1920 INVENTORS Burwell E Day 6 CIlYfOrdADZ M'eber WITNESSES: fi JQ'KLMamu/z/ flaw ATTORNEY Patented May 13, 1924.

UNITED STATES PATENT OFFICE.

BURWELL F. DAY, OF WILKINSIBURG, AND CLIFFORD A. M. WEBER, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC t MANUFAC- TURING COMPANY, A CORPORATIONOF PENNSYLVANIA.

CENTRIFUGAL SWITCH.

Application filed June 17, 1920. Serial No. 389,548.

To all whom it may concern Be it known that we, BURWELL F. DAY, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, and CLIFFORD A. M. Wanna, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Centrifugal Switches, of which the following is a specification.

Our invention relates to centrifugal switches and it has particular relation to switches employed for opening and closing electric circuits when rotating members attain predetermined speeds, such, for ex ample, as switches employed for disconnecting starting windings of single-phase motors at redetermined speeds.

.The ol iject of our invention is to provide a switch which shall eliminate all pm-andslot connections, shall be relatively compact and inexpensive in construction, of great reliability and quick and positive in its action.

Another object of our invention is-to provide a centrifugal device which will operate a stationary member of a switch, if the rotor u on which the device is mounted is stopped a 0st instantly or within a fraction of a revolution.

Heretofore, it has been customaryto provide the rotating portion of a switch with a plurality of arms having projecting portions which move in slots in the adjacent arms in order to insure uniform movement of all of the arms. The sliding of one surface over another surface, especially in a pin-and-slot connection, caused a certain amount of friction and ultimate wear which resulted in the surfaces about the slots becomin so irregular that the rotating portion 0% the switch did not properly contract upon a decrease in speed after being opened by rotation at a hig er speed.

By our invention, we provide a centrifugal switch, the rotatin portion of which is so constructed that, w en a predetermined speed is attained, the rotating arms will open or close rapidly, with relatively great force, thereby actuating the stationary part of the switch, the rotating device being so designed that there are ing in grooves or slots, tiereby lessening friction and the wear resulting therefrom.

Briefly speaking, our invention consists of pivotally mounting two arms on a rotatable base and so attaching auxiliary arms thereto that the inward and outward movements of the arms are alwa s equal. The travel of the arms is confined to certain limits and they are so maintained in a closed position by resilient members that they do not open outwardly until the base upon which they are mounted is rotated beyond a predetermined speed.

A better understanding of our invention may now be had by reference to the accompanying drawings, Figs. 1 and 2 of which are views, in side elevation and 111 end elevation, of the stationary portion of a centrifugal switch.

Figs. 3 and 4 are views, in side and end elevation, respectively, tion of the switch which embodies our invention.

Figs. 5 and 6 are detail views of an arm shown in Figs. 3 and 4.

Figs. 7 and 8 are corresponding views of an auxiliary arm which is also shown in Figs. 3 and 4.

Fig. 9 is a diagrammatic view of a singlephase motor showing the application of our switch thereto. 7

Fig. 10 is a diagrammatic view of the movement of the pivots upon which the arms are mounted, as shown 1n Figs. 3 and 4.

Referring particularly to Figs. 1, 2, 3 and 4, a centrifugal switch 11 comprises a stationary part 12 and a rotating part or centrifugal device 13 (shown in Figs. 3 and 4). The stationary portion 12 of the switch 11 comprises a base plate 14 in which a carria e 15 is slidably mounted. This portion of the switch has been described in detail in Letno rojections mov of the rotating porters Patent to J. B. Hansell, dated May 27, 1919, and numbered 1,305,094. When the carriage 15 is in the position shown in the drawing, a bridging member 16 mounted thereon completes an electrical circuit through the stationary contact members 17. Springs 18 cause the rapid outward or inward movement of the carriage when it passes a predetermined point. The carriage 15 is provided with lugs 19 and 20 wh ch are engaged by the rotatable part 13 of the switch 11.

The rotatable part or composite ring 13 is shown in F i s. 3 and 4 and comprises an annular base p ate 21 provided with a circular opening 22 through which extends a rotatable shaft 23 (shown only in Figs. 2 and 4). The plate 21 may be secured directly to the shaft 23 or it may be fixedly mounted upon a rotor core member (not shown). The plate 21 is provided with two lugs 24 which are diametrically opposed to each other at the outer circumference of the plate. A. main arm 25 is pivotally mounted upon each of the lugs 24 by means of rivets 26. Each arm 25 is provided with a rivet 27 by which it is pivotally attached to an oppositely disposed auxiliary arm 28. The auxiliary arms are, in turn, mounted upon the adjacently disposed arms 25 by means of rivets or bolts 27a. The auxiliary arms 28 cause the main arms 25 to move outwardly and inwardly together.

In Figs. 5 and 6, an arm 25 of crescent or similar shape is shown provided with an additional plate 29 secured, thereto by counter sunk rivets 30 for increasing the weight thereof and for moving the center of gravity a greater distance from the rivet 26, about which the arm 25 turns. The rivets 27 and 27a for securing auxiliary arms 28 are also shown in this view.

Figs. 7 and 8 show the auxiliary arm 28, likewise of crescent or simeter shape, provided with holes 31 for the rivets 27 and 27a by which it is pivotally mounted upon the main arms 25. The arm 28 is also provided with an end projection 32 and a lug or a projection 33 extending perpendicularly to the plane of the arm 28. The end projection 32 of the auxiliary arm 28 limits the outward movement of the arm by engaging the lug 24 and it engages the inner lug 20 of the carriage 15 when the centrifugal device 13 contracts. The auxiliary arms 28 ensure the inward movement of the carriage 15, if the device 13 should be stopped so suddenly that the main arms 25 do not engage the lug 20. The lug or projection 33 prevents the arm 28 from vibrating in a plane perpendicular to the plane in which the arm 28 rotates.

Referring again to Figs. 3 and 4, springs 34, which maintain the arms 25 and 28 in the closed position shown in the drawing, are attached to the lugs 24 of the base plate 21 and to the lugs 33 of the auxiliary arms 28 by means of holes 35 in the lugs 24 and 33.

The inward movements of the arms 25 are limited by the engagement of the opposite ends thereof. The outward movements of aeeaeae the arms 25 are limited by the end projections 32 of the auxiliary arms 28 engaging the lugs 24.

Fig. 10 is a diagrammatic view lllustrating the principle underlylng the operat on of our switch. The rivets 26, about whlch the arms 25 turn, are in fixed relation to each other. The rivets 27 and 270, about which the auxiliary arms turn, are always in parallelogram relation to each other, because the shorter distances 25a are constant and e ual, being determined by the arms 25, and t e longer distances 28a are likewise constant and equal with respect to each other, being determined by the auxiliary arm 28.

Fig. 9 shows, diagrammatically the relation of the centrifugal switch ll to the auxiliary winding 37 and the main field winding 38 of a dynamo-electric machine 39. When the dynamo-electric machine 39 attalns a predetermined speed, the auxiliary winding 37 is disconnected from the circult by means of the centrifugal switch 11, leaving the main field winding 39 electrically energized.

When the dynamo-electric machine 39 is at rest, the rotating part 13 of the switch 11 is in the position shown in Figs. 3 and 4, the outer edge of which forms substantially a circle. When the dynamo-electric machine 39 is so operated that the shaft 23 attains a predetermined speed, the arms 25 are forced outwardly to a position shown by broken lines in Fig. 3, the inner edges of the arms forming substantially a circle, by the centrifugal force becoming greater than theopposing force of the helical springs 34. The arms 25 are so designed that the center of gravity of each is relatively removed from the point about which the arm is pivoted, causing it to open with great rapidity, as the resistance of the spring 34 increases at a relatively slow rate. The arms 25, moving outwardly, engage the In 19 of the carriage 15 and force it outwar ly, the springs 18 causing the action to occur with great rapidity, whereby the circuit of the auxiliary winding will be broken very quickly. When the shaft 23 rotates at less than a predetermined speed, the arms 25 and the auxiliary arms 28 close and, engaging the lug 20 of the carriage 15, force it to return to a closed position.

It will be observed by those skilled in the art that, by our invention, we provide a centrifugal switch which opens and closes quickly and positively at predetermined speeds, which has no slots or grooved portions to cause friction and wear, and which is so arranged that the arms will remain in uniform relation to each other throughout their movement and will not remain in an open position when centrifugal force is no longer applied.

While we have shown our invention in a preferred form it may be subject to slight modifications without departing from the spirit thereof; therefore, we desire to be limited only by the scope of the appended claims.

We claim as our invention 1. A centrifugal device comprising a supporting member adapted to be secured to a rotating member, a pair of diametrically disposed supporting pivots on said supporting member, a pair of arcuate-shaped weight arms mounted upon said pivots, respectively, each of said weight arms having a portion extending beyond its supporting pivot, a pair of arcuate-shaped equalizer arms connecting said weight arms, said equalizer arms being pivoted to said weight arms at points equidistant from said supporting pivots and on opposite sides thereof, whereby the center lines of said equalizer arms are substantially parallel, and a pair of tension springs symmetrically mounted between the supporting member and one of said pairs of arms, the connecting points of said springs being such that the increase in the spring tension produced by the outward movement of the weight arms is slight compared to the increase in the centrifugal force produced by said outward movement.

2. A centrifugal device comprising a supporting member adapted to be secured to a rotating member, a pair of lugs or spacing members extending from said supporting member at diametrically opposite points, a pair of arcuate-shaped weight arms pivotally mounted on said lugs, respectively, to lie in spaced relation to said supporting member, each of said weight arms having a portion extending beyond its supporting pivot, a pair of arcuate-shaped equalizer arms connecting said weight arms, said equalizer arms being pivoted to said weight arms at points equidistant from said supporting pivots and on opposite sides thereof, whereby the center lines of said equalizer arms are substantially parallel, members offset from said equalizer arms intermediate the ends thereof and extending toward said supporting member, and a pair of tension springs symmetrically mounted between said lugs and said offset members.

3. A centrifugal device comprising a supporting member adapted to be secured to a rotating member, a pair of lugs or spacing members extending from said supporting member at diametrically opposite points, a pair of arcuate-shaped weight arms pivotally mounted on said lugs, respectively, to lie in spaced relation to said supporting member, each of said weight arms having a portion extending beyond its supporting pivot, a pair of arcuate-shaped equalizer arms connecting said weight arms, said equalizer arms being pivoted to said weight arms at points equidistant from said supporting pivots and on opposite sides thereof, whereby the center lines of said equalizer arms are substantially parallel, members offset from said equalizer arms intermediate the ends thereof and extending toward said supporting member, and a pair of tension springs symmetrically mounted between said lugs and said offset members, said equalizer arms being disposed on the side of said weight arms adjacent said supporting member and having an abutment engaging said lugs to limit the outward movement of said weight arms.

4. A centrifugal device comprising a supporting member adapted to be secured to a rotatingemember, a pair of lugs or spacing mem rs extendin from said supporting member at diametrically opposite points, a pair of arcuate-shaped weight arms pivotally mounted on said lugs, respectively, to lie in spaced relation to said supporting member, each of said weight arms having a portion extending beyond its supporting pivot, a pair of arcuate-shaped equalizer arms connecting said weight arms, said equalizer arms being pivoted to said weight. arms at points equidistant from said sup porting pivots and on opposite sides thereof, whereby the center lines of said equalizer arms are substantially parallel, members offset from said equalized arms intermediate the ends thereof and extending toward said supporting member, and a pair of tension springs symmetrically mounted between said lugs and said offset members, said equalizer arms being disposed on the side of said weight arms adjacent said supporting member and having an abutment engaging said lugs to limit the outward movement of said weight arms, and each of said weight arms having a lug for contacting with a portion of the other weight arm to limit the inward movements of said arms.

5. A centrifugal device comprising a supporting member adapted to be secured to a rotating member, a pair of diametrically disposed supporting pivots on said supporting member, a pair of arcuate-shaped weight arms mounted upon said pivots, respectively, each of said weight arms having a portion extending beyond its supporting pivot, means for maintaining the movements of said arms uniform with respect to each other, resilient means for retaining said arms in closed positions until said members are rotated at a predetermined speed, and a lug on each of said weight arms for contacting with a portion of the other weight arm to limit the inward movements of said arms.

6. The combination with a rotatable shaft, of a mechanism operable thereby and comprising a fixed guide member and a reciproeating carriage movable transversely to said shaft, said carriage having lugs for moving the same outwardly and inwardly and a centrifugally actuated device mounted upon said shaft and operable to move said carriage in the one or the other direction in accordance with the speed of rotation of said shaft, said centrifugally actuated device comprising a base member, two arcuate weight arms pivotally mounted upon said base member at diametrically opposite points, said weight arms having contact surfaces for co-operating with said lugs for moving said carriage outwardly and inwardly, a pair of arcuate equalizer arms connecting said weight arms to cause the same to move in unison, said equalizer arms having contact surfaces circumferentially spaced from the corresponding contact surfaces or said weight arms for engaging the inner lug of said carriage for moving the same inwardly, and resilient means for restraining said weight arms against outward movement.

7. The combination with a rotatable shaft. of a mechanism operable thereby and comprising a fixed guide member and a reciprocating carriage movable transversely to said shaft, said carriage having lugs for moving the same outwardly and inwardly, and a centrifugally actuated device mounted upon said shaft and operable to move said carriage in the one or the other direction in accordance with the speed of rotation of said shaft, said centrifugally actuated device comprising a base member, two arcuate weight arms pivotally mounted upon said base member at diametrically opposite points, said weight arms having contact surfaces for co-operating with said lugs for moving said carriage outwardly and inwardly, a pair of arcuate equalizer arms connecting said weight arms to cause the same to move in unison, said equalizer arms having contact surfaces circumferentially spaced from the corresponding contact surfaces of said weight arms for engaging the inner lug of said carriage for moving the same inwardly, resilient means for restraining said weight arms against outward movement, means for limiting the inward and outward movements of said weight arms, and means for normally causing said carriage to occupy either a fully-in position or a fully-out position wherein said lugs are out of contact with said contact surfaces.

8. The combination with a rotatable shaft, of a switching mechanism operable thereby and comprising a reciprocating carriage movable transversely to said shaft and a fixed switch member, and a centrifugally actuated device mounted upon said shaft and operable to move said carriage in the one or the other direction and to cause engagement with or disengagement from said switch member in accordance with the speed of rotation of said shaft, said centrifugal actuating device comprising a base member, two arms pivotally mounted upon said base member and moving in substantially the same plane, said arms being oppositely disposed one from the other, of means for limiting the inward and the outward movement of said arms and for equalizing said movements, and resilient means for maintaining said arins in closed positions until said arms are acted upon by a predetermined centrifugal force, said arms and equalizing means both having contact surfaces for efiecting the movement of said carriage.

9. The combination with a stationary switch mechanism, of a centrifugally actuated device for operating said mechanism comprising a rotatable member provided with lugs or spacing members, two main arms pivotally mounted upon said lugs and turning in substantially the same plane, two auxiliary arms pivotally mounted upon said main arms, and resilient means for maintaining said arms in closed positions until said member is rotated faster than a predetermined speed.

10. The combination with a rotatable member provided with lugs, of two main arms pivotally mounted upon said member and turning substantially in the same plane, an auxiliary arm pivotally mounted upon one of said main arms so as to be relatively adjacent to said lug, and a spring secured to said auxiliary arm and one of said lugs.

In testimony whereof, we have hereunto subscribed our names this 3rd day of June, 1920.

BURWELL F. DAY. CLIFFORD A. M. WEBER. 

